Molecular systematics of orchidaceae: a literature review and an example using five plastid genes

Cameron K.M., . (2005) Molecular systematics of orchidaceae: a literature review and an example using five plastid genes. [Proceedings Paper]

Phylogenetic relationships among subfamilies and tribes of Orchidaceae were investigated using DNA sequences from 35 exemplar orchid genera and one outgroup taxon from Hypoxidaceae. Data from five plastid genes rbcL atpB psaB ndhF and matK were analysed separately and in combination. The combined data matrix consists of 241 726 individual nucleotide characters making it one of the largest molecular data matrices for Orchidaceae published to date. Trees from individual gene matrix analyses are generally congruent in terms of inter-subfamilial relationships but vary in overall resolution bootstrap support for particular clades and especially for relationships among the genera of Epidendroideae. The combined five-gene tree however is well resolved and supported especially when successive weighting is applied to the matrix. Epidendroideae and most of its tribes are monophyletic. The subfamily is sister to Orchidoideae which includes the spiranthoid orchids: Cypripedioideae is sister to this pair of monandrous subfamilies. Vanilloideae is sister to these three and Apostasiodeae is sister to the entire remainder of the family. With this limited level of taxon sampling branch lenghts are long among all the taxa except for the higher epidendroid orchids. The tree topology indicates that this particular lineage of mostly epiphytic orchids underwent a rapid evolutionary radiation with high rates of subsequent speciation perhaps in quite recent geologic history. The implications of molecular studies such as this for the taxonomy and calssification of Orchidaceae are discussed and an up-to-date review of the molecular systematics literature for the family is presented.

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Abstract

Phylogenetic relationships among subfamilies and tribes of Orchidaceae were investigated using DNA sequences from 35 exemplar orchid genera and one outgroup taxon from Hypoxidaceae. Data from five plastid genes rbcL atpB psaB ndhF and matK were analysed separately and in combination. The combined data matrix consists of 241 726 individual nucleotide characters making it one of the largest molecular data matrices for Orchidaceae published to date. Trees from individual gene matrix analyses are generally congruent in terms of inter-subfamilial relationships but vary in overall resolution bootstrap support for particular clades and especially for relationships among the genera of Epidendroideae. The combined five-gene tree however is well resolved and supported especially when successive weighting is applied to the matrix. Epidendroideae and most of its tribes are monophyletic. The subfamily is sister to Orchidoideae which includes the spiranthoid orchids: Cypripedioideae is sister to this pair of monandrous subfamilies. Vanilloideae is sister to these three and Apostasiodeae is sister to the entire remainder of the family. With this limited level of taxon sampling branch lenghts are long among all the taxa except for the higher epidendroid orchids. The tree topology indicates that this particular lineage of mostly epiphytic orchids underwent a rapid evolutionary radiation with high rates of subsequent speciation perhaps in quite recent geologic history. The implications of molecular studies such as this for the taxonomy and calssification of Orchidaceae are discussed and an up-to-date review of the molecular systematics literature for the family is presented.

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Item Type:	Proceedings Paper
Additional Information:	Summary En
AGROVOC Term:	ORCHIDACEAE
AGROVOC Term:	PLASTIDS
AGROVOC Term:	GENES
AGROVOC Term:	MOLECULAR GENETICS
AGROVOC Term:	GENETICS
AGROVOC Term:	GENOMES
AGROVOC Term:	PHYLOGENY
AGROVOC Term:	HYPOXIDACEAE
AGROVOC Term:	DNA
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:27
URI:	http://webagris.upm.edu.my/id/eprint/16535

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